Yoko Ono and her son, Sean Lennon, speaking in New York during a news conference, launched Artists Against Fracking, the main celebrity-driven anti-fracking campaign.

Bebeto Matthews/Associated Press file photo

Yoko Ono and her son, Sean Lennon, speaking in New York during a news conference, launched Artists Against Fracking, the main celebrity-driven anti-fracking campaign.

NEW YORK – The scene: a Manhattan art-house theater. The cause: a campaign against the gas drilling process known as fracking that’s being led by more than 100 celebrities, including Yoko Ono, Sean Lennon, Robert Redford, Mark Ruffalo and Mario Batali.

Outside, demonstrators in hazmat suits circle the theater. Inside, actress Scarlett Johansson attends a benefit screening of “Gasland,” the documentary film that has become the movement’s manifesto. Johansson tells The Associated Press that her “Avengers” co-star Ruffalo introduced her to the cause, and that she found the film “incredibly shocking.”

The campaign has galvanized hundreds of thousands of followers, but as with many activist causes, the facts can get drowned out by the glitz. Now, some experts are asking whether the celebrities are enlightened advocates or NIMBYs – crying “Not in my backyard!” – even as their privileged lives remain entwined, however ruefully, with fossil fuels.

Much of the anti-fracking activism is centered in New York City, where concerts, movies and plays use huge amounts of energy, gourmet chefs including Batali cook with gas, and most people – the glitterati included – heat with gas.

There’s no doubt that critics of hydraulic fracturing – a practice colloquially known as fracking that involves injecting water, sand and chemicals into underground rock to free vast reserves of gas – have some legitimate concerns. There have been documented cases of leaking gas ruining nearby well water, of air pollution and of problems from the waste the drilling generates. Experts say those are important parts of the story – but far from the whole story.

“With proper regulation and enforcement, gas provides a very substantial health benefit in reducing air pollution,” compared with coal-fired power plants, said Daniel Schrag, director of Harvard University’s Center for the Environment.

That is a theme not adequately covered in the debate over fracking, agreed Michael Greenstone, an environmental economics professor at the Massachusetts Institute of Technology and a former top adviser to the Obama administration. Greenstone is studying the local health effects of fracking, but he said it’s not scientifically accurate to ignore “the tremendous health gains” from the coal-to-gas shift.

“Honestly,” he said, “the environmentalists need to hear it.”

The main celebrity anti-fracking campaign took off last summer when Ono and Lennon, her son, founded Artists Against Fracking. Their family farm sits near gas reserves in New York, and they fear fracking might be allowed in the area.